View Compilation Error

0_0_37695516_13544.cpp: In function 'LL get_eulars(LL)':
0_0_37695516_13544.cpp:9:22: error: 'n' was not declared in this scope
  for(int i = 2; i <= n / i; i ++)
                      ^
0_0_37695516_13544.cpp:17:5: error: 'a' was not declared in this scope
  if(a > 1) res = res / a * (a - 1);
     ^